The invention relates to a device for operating at least one swirling device which controls the flow rate of combustion air of a burner for gas turbine engines.
A known burner for gas turbine engines has at least one swirling device which can be controlled with respect to the flow rate of combustion air. This swirling device consists of a ring body which is coaxial to the nozzle and forms openings between profiles distributed uniformly along the circumference. Radially bent fingers of a sleeve engage in the openings. The sleeve is arranged in an axially adjustable manner on the outside on the ring body.
In this known burner, the fingers are web-type control bodies. These control bodies are constructed and arranged in such a manner that flow cross-sections can be adjusted which are variable in view of the axial sleeve adjustment and remain constant along the overall length. In this fashion, on at least one swirling device of a burner, the air flow rate operationally required for a low-pollutant and homogeneous combustion is made possible while a continuously uniform air swirl formation and therefore rotational swirl formation is maintained in the combustion chamber. In addition, a controllable air supply for additional primary air can be "superimposed" on at least one stationary swirling device in order to achieve a low-pollutant combustion in adaptation to the respective operating and load condition.
Particularly in view of an application in an annular combustion chamber, the above-mentioned device provides the use of a mechanically actuated adjusting system in order to be able to adjust all sleeves of the swirling devices simultaneously as a function of the load condition. The swirling devices are part of burners uniformly distributed along the circumference. In this case, the mechanical adjusting system comprises, among other components: an adjusting ring which is rotatably disposed on the circumference of the combustion chamber housing and to which one group of free ends of levers are pivotally connected. At the respective other end, the levers engage in a recess on the circumference of the respective sleeve. In addition, the levers each have an arm with a guide slot that is sloped relative to the burner axis. A pin, which in each case is fixedly connected with the respective sleeve, engages in the guide slot. An adjusting system of this type requires relatively heavy, cost-intensive, high constructional expenditures. In addition, it is susceptible to wear and disturbances. Also, the components of the adjusting system are subjected to load-cycle-dependent thermal differential expansions which may lead to adjusting inaccuracies and, in extreme cases, in component jamming.
There is therefore needed a device for at least one burner in accordance with the above-mentioned type which, while its construction is relatively simple, ensures a disturbance-free and reliable adjustment and control of the respective at least one burner-side swirling device.
These needs are met according to the present invention by a device for operating a swirling device which controls the flow rate of combustion air of a burner for gas turbine engines. The swirling device comprises on the head end of a combustion chamber a ring body with swirling ducts. The ring body is arranged coaxially with respect to the fuel nozzle. The cross-sections of the swirling ducts are controllable by means of duct walls of a ring which is axially displaceable on the ring body. The axial displacement of the ring takes place by means of a control piston which is axially displaceable in a housing, is spring-loaded on one side, is actuated by a valve-controlled pressure difference existing on the spring side between an ambient pressure and a primary-air pressure, and controls openings communicating with the valve and the head end of the combustion chamber and which, on piston surfaces which are free with respect to the housing, on the one side, is acted upon by pressure of supplied primary air existing on the head end, and, on the other side, is acted upon by chamber pressure existing at the burner.